1. Field of the Invention
The present invention relates to a fluorescence detecting apparatus, and a fluorescence detecting method.
2. Description of the Related Art
Fluorescence is emitted from a fluorescent material when excitation light is emitted onto the fluorescent material. Heretofore, there have been reported various fluorescence detecting apparatuses for detecting the position of a specific portion with respect to an object to be measured (hereinafter, called as a “measurement object”) by impregnating a fluorescent material into the measurement object, and sensing fluorescence to be emitted from the measurement object irradiated with excitation light. In the fluorescence detecting apparatuses, it is necessary to obtain an entire image of the measurement object, as well as a fluorescent image, in order to detect the position of a specific portion with respect to the measurement object. However, an image pickup condition i.e. an exposure condition such as a shutter speed and an aperture differs between a case where an image of a measurement object is obtained, and a case where a fluorescent image is obtained. Accordingly, it is not easily to display a fluorescent image and a measurement object image on an identical display screen. In the following, some of the conventional fluorescence detecting apparatuses are described.
For instance, Japanese Unexamined Patent Publication No. 2006-122131 (D1) discloses an apparatus provided with an image pickup device for capturing a fluorescent image, and an image pickup device for capturing an entire image of a measurement object. Image pickup operations are performed individually in respective optimum image pickup conditions by the image pickup devices. After the image pickup operations, the position of the fluorescent portion with respect to the entirety of the measurement object is detected by combining the fluorescent image and the measurement object image.
Japanese Unexamined Patent Publication No. 2006-14868 (D2) discloses a single image pickup device. The image pickup device is operable to sequentially capture a fluorescent image and an entire image of a measurement object in respective optimum image pickup conditions with a time lag. After the image pickup operations, the position of the fluorescent portion with respect to the entirety of the measurement object is detected by combining the fluorescent image and the measurement object image.
Japanese Unexamined Patent Publication No. 2000-354583 (D3) discloses a single image pickup device. The image pickup device is operable to simultaneously capture a fluorescent image and an entire image of a measurement object. In capturing the measurement object image, the light amount of illumination light is reduced by attaching a filter to an illumination light source for illuminating the measurement object. This enables to simultaneously capture a fluorescent image and a measurement object image without a likelihood that a fluorescent image may not be distinguished from the measurement object image. In other words, attaching a filter to the illumination light source for illuminating a measurement object enables to define an image pickup condition optimum for capturing both a fluorescent image and a measurement object image. The position of the fluorescent portion with respect to the entirety of the measurement object is detected based on an image captured by the image pickup device.
Japanese Unexamined Patent Publication No. 2003-79570 (D4) discloses a single image pickup device. The image pickup device is operable to capture a fluorescent image and an entire image of a measurement object with a time lag. After the image pickup operations, the position of the fluorescent portion with respect to the entirety of the measurement object is detected by combining the fluorescent image and the measurement object image. The image pickup device is also operable to capture a fluorescent image and an entire image of a measurement object in respective optimum image pickup conditions by changing a charge multiplication ratio of the image pickup device depending on a receiving light amount. After the image pickup operations, the position of the fluorescent portion with respect to the entirety of the measurement object is detected by combining the fluorescent image and the measurement object image.
The apparatus disclosed in D1 has two image pickup devices. Accordingly, the size and the cost of the apparatus may be increased.
The image pickup device disclosed in D2 captures a fluorescent image and a measurement object image with a time lag. Accordingly, in the case where the measurement object is moved in a time between the image pickup operations, positional displacement may occur between the fluorescent image and the measurement object image.
In the image pickup device disclosed in D3, the light amount of illumination light is reduced by attaching a filter. However, the reduced amount of illumination light is unchanged. Accordingly, there is a likelihood that a fluorescent image may not be distinguished from a measurement object image, depending on the intensity of fluorescence.
Similarly to the image pickup device in D2, the image pickup device disclosed in D4 captures a fluorescent image and a measurement object image with a time lag. Accordingly, in the case where the measurement object is moved in a time between the image pickup operations, positional displacement may occur between the fluorescent image and the measurement object image. Also, since the charge multiplication ratio of the image pickup device is predefined, a desirable image may not be obtained depending on a measuring condition.